Check https://getcomposer.org/doc/articles/troubleshooting.md#memory-limit-errors for more info on how to handle out of memory errors.
{"messages":{"error":[{"code":500,"message":"Fatal Error: 'Allowed memory size of 134217728 bytes exhausted (tried to allocate 4096 bytes)' in '/home/a1pro/public_html/magento/vendor/magento/framework/ObjectManager/Factory/AbstractFactory.php' on line 121"
when i checked during command then it shows 128M only. but i have changed with php_value memory_limit 2048M .